Transcending Time: Great Long-Term Datasets

Escaping the boundaries of human perspective is a fundamental task of science. Telescopes cross distance; microscopes, size; other tools detect sounds beyond hearing or light beyond sight.
Datasets spanning years and decades allow patterns to emerge on scales outside the days and weeks of customary attention.

In the 20th century, biologists, ecologists and epidemiologists launched many long-term studies, designed with an eye beyond their own time. More recently, researchers have mined records — from captains' logs to Google Books — that in retrospect contain useful data. The approaches embody some of science's great virtues: foresight, patience and cleverness.

On the following pages, Wired Science presents some of its favorite long-term datasets.

Above: Japanese Cherry Blossom Festivals

In Japan, cherry blossom festivals are an ancient and wildly popular tradition, featuring days-long celebrations carefully timed to coincide with peak flowering. The festivals are so prominent in Japanese culture that their collective descriptions in diaries, literature and administrative records have been turned into a six-century-long record of blossoming dates and locations across the islands.

Images: Above) Kazuhiko Teramoto/Flickr Below) Top row, the known dates of full cherry flowering from the 11th century to present. April 1 is the year's 91st day, and May 1 is the 122nd. Bottom row, estimated historical March temperatures as calculated from flowering dates. (Yasuyuki Aono & Yuko Omoto/Journal of Agricultural Meteorology)

Continuous Plankton Recorder

Designed in 1931 by marine biologist Alister Hardy, the Continuous Plankton Recorder is a biopunk-named, nondescript-looking steel box containing two skeins of silk mesh. When it's dipped into the sea, plankton are trapped between them.

Since sampling methods were formalized in 1948, nearly 300 ocean-crossing ships have carried CPRs from their bows. Sample by sample, over millions of miles, they've produced a global record of activity at the base of oceanic food chains.

Chillingham Cattle

The wild cattle of Chillingham, England have been studied since 1860, when their original owner was encouraged in record-keeping by none other than Charles Darwin, a man uniquely positioned to appreciate long-term datasets.

Since the 1950s, Chillingham cows calved during winter with increased frequency. This appears to be a function of climate change: Warmer springs result in earlier vegetation growth, which result in earlier mating. Unfortunately for calves, winter is a difficult time to be born.

Images: Above) Chillingham cattle. Yellow Book/Flickr Below) Proportion of births occurring in each season per year over a 62-year period. (Burthe et al./Journal of Animal Ecology)

Florida Fishing Trip Photographs

Fish stories are synonymous with tall tales, but photographs are another matter, and snapshots taken by charter boat operators in Key West, Florida provide year-by-year documentation of an ecosystem in transition. Overfishing and reef destruction almost eliminated large fish, then medium-sized fish, finally leaving only the small ones.

Images: Above) Trophy fish caught on a Key West charter boat in 1957 (Loren McLenachan/Conservation Biology) Below) Top, fish caught in the early 1980s; middle, fish caught in 2007; and at bottom, species composition of displayed fish arranged in order from largest to smallest. (Loren McLenachan/Conservation Biology)

Isle Royale Wolves

During an especially deep winter in 1949, two wolves from Ontario crossed a frozen Lake Superior, arriving at Michigan's Isle Royale. The island teemed with moose, and the pair stayed; nine years later, Purdue University wildlife ecologist Durward Allen started to study them. They've been monitored ever since in what may be the single longest-running study of any animal population.

A trove of fantastically detailed information has been gathered about the wolves, such as the exact locations where they've killed 3,654 moose since 1958. In recent years, chemical analysis techniques have allowed Isle Royal researchers to quantify the flow of nutrients that represents, with each carcass ultimately feeding plants and animals over three square acres. From this perspective, wolves don't simply kill moose; they spread life across the island.

Images: Above) Wolves and pup. (United States Department of Agriculture/Man and Biosphere Program) Below) Top left, a wolf-killed moose carcass; top right, the same carcass three days later. In the middle is a map of moose carcass density between 1958 and 1982; below, a map of changes in carcass density between that period and 1983-2006. (Bump et al./Ecology)

E. coli Long-Term Experimental Evolution Project

Long-term studies of animals like the Chillingham cattle and Isle Royale's wolves can hint at evolutionary trends, but a deeper picture of evolution requires hundreds or thousands of generations. At Michigan State University, microbiologist Richard Lenski has tracked 12 once-identical Escherichia coli populations that were seeded in 1988 and have evolved independently ever since, a period of time spanning 50,000 generations.

Lenski's E. coli strains are now distinct, each possessing unique adaptations and traits, and research on them has deepened scientific understanding of evolution's underlying principles — such as the very nature of evolvability itself.

Google Books

Cultural evolution clearly happens, but it's difficult to study with the formal rigor of biological evolution. With a few exceptions, such as anthropological monographs of canoe design in Polynesia, the data's just too messy.

Framingham Heart Study

In 1948, some 5,209 adult residents of Framingham, a blue-collar Massachusetts town, enrolled in what would become the longest-running epidemiological study ever. Nothing like it had been done; the participants would submit to medical checkups every year, eventually giving researchers a large-scale, long-term picture of human health.

The study is now on its third generation; much of what's now considered bedrock conventional wisdom about heart disease and stroke — such as their links to cigarette smoking, high cholesterol and high blood pressure — were actually groundbreaking insights from Framingham.

Images: Above) Walter Sullivan and Jane Klug, two of the Framingham Heart Study's founders and original participants, photographed in October 2010. (Framingham Heart Study) Below) Correlation of stroke mortality risk (y-axis) and blood pressure (x-axis) with age in men and women. (Lewington et al./Lancet)

20th Century Reanalysis Project

Completed just this year, the 20th Century Reanalysis Project combines historical records from a hodgepodge of sources — the records of sea captains and explorers, doctors and old news accounts — into detailed weather maps, giving the late-19th and 20th centuries a modern level of meteorological coverage.

The Hutton Unconformity

Though geology is almost by definition a study of long-term datasets, an exception should be made for one: a hillside in Jedburgh, Scotland where layers of ancient schist drive upward into layers of slightly less ancient sandstone, dramatically illustrating the wild ideas of 18th-century doctor and geologist James Hutton.

In 1787, when Hutton first saw the so-called unconformity that would later bear his name, it was widely believed that Earth was about 6,000 years old. Hutton, however, believed that modern rock formations resulted from violent upheavals conceivable only in terms of deep time. It was a bold, even heretical claim, and required a bold demonstration. The jagged stratification of Jedburgh, so different than the smooth schist-and-sandstone layering seen elsewhere in Scotland, would provide it.

"Alive in a world that thought of itself as 6,000 years old, a society which had placed in that number the outer limits of its grasp of time, Hutton had no way of knowing that there were 70 million years just in the line that separated the two kinds of rock, and many millions more in the story of each formation," wrote John McPhee of Hutton in Annals of the Former World. "But he sensed something like it, sensed the awesome truth, and as he stood there staring at the riverbank he was seeing it for all humankind."

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